Assuming you pass the input file as an argument and redirect the output to your output file, i.e. that you use a syntax like this for launching the program under your shell:

perl script.pl test2.csv > final.csv
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then the script itself can be something like this:

use strict;
use warnings;
while (my $line = <>) {
    chomp $line;
    print "$line", " ,UF, A, Y, 9, U\n";
}
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